Peter Bouckaert, a researcher for the group working out of the rebel stronghold of Benghazi, said in the statement that both antivehicle and antipersonnel mines had been found in the ground. An electrical utility truck ran over and detonated two antipersonnel mines on Monday, and 24 antivehicle mines and more than 30 antipersonnel mines were later removed from the same area. No injuries were reported.

Because of the location, on the eastern outskirts of the city, and traffic around the area, Mr. Bouckaert concluded that the mines were planted by Qaddafi forces during the 10 days ending March 27 when Colonel Qaddafi last controlled Ajdabiya. A Libyan government stockpile of more mines was discovered in an arms depot in Benghazi as well.

The discovery of the mines could add to the case justifying international intervention in Libya on the grounds that if unchecked Colonel Qaddafi would threaten civilians in areas where rebels are challenging his four decades in power. Many countries have rejected the use of land mines because of their disproportionate toll on civilians, sometimes for decades after they were laid.

Libya is last known to have used land mines in its war with Chad during the 1980s. While most nations have signed a treaty restricting their use, the Qaddafi government has defended its right to employ them to defend Libya’s long borders.